Application: Beams, slabs, frames or complete structures can be subjected to static loads as limited by test floor capacity or cyclic loads up to 50,000 pounds with programmed amplitude and frequency. Signals in the range of 0 to 300 volts from load cells, strain gages, pressure transducers, LVDT's, and other types of electromechanical sensors are recorded on magnetic type and optionally printed on teletypewriters. Availability: When not otherwise in use and when staff is available to prepare the facility for the user. Literature:

[1] Achenbach, P. B., Building Research at the National Bureau of Standards, Nat. Bur. Stand. (U.S.) Bldg. Sci. Ser. No. 0 (Oct. 1970). [2] Yokel, F. Y. and Somes, N. F., Structural Performance Evaluation of Innovative Building Systems, ibid Tech. Note 706 (Aug. 1972). Contact: Dr. R. A. Crist, Chief of Structures Section, Building Research Building, Room B168, Phone 301921-3471.

THERMAL ENGINEERING LABORATORIES

This group of five laboratories permits performance testing of refrigeration and air conditioning equipment, heating systems, and insulating materials. Well controlled conditions of temperature and humidity are maintained in large test chambers. An analog and digital data logging system is available for 300 sixdigit channels for 0.1 to 1000 volt inputs.

Capabilities: The Air Cleaning Laboratory contains a test duct capable of maintaining flows of 50 to 2500 cfm through a 2 ft X 2 ft device; also equipment for particle counting, dust sampling, and NBS dust spot efficiency. Air cleaners can be tested, anemometer scans checked, and field evaluation of dust problems made.

The Air Conditioner and Heat Pump Laboratory includes an indoor room 39 ft X 13 ft X 21 ft, controlled for 40°F to 140°F, and 50% rh at 35°F to 85°F dew

point at 120°F; and an outdoor room 20 ft X 13 ft X 21 ft, controlled for -10°F to 150°F. Heat pumps may be tested in either the winter or the summer mode.

The Environmental Laboratory, 49 ft X 42 ft X 31 ft, is controlled for -46°C(-50°F) to 66°C(150°F), and 50% rh at 35°F to 85°F dewpoint at 120°F. Supply air is furnished by ceiling diffusers; damper-controlled air ducts in all eight corners of the room permit good air distribution. The floor is earth and may be excavated. Thermal performance or heating and cooling load measurements can be made either on models or on full-scale building constructions or equipments.

The Refrigeration Laboratory, 49 ft X 20 X 17 ft, is controlled for -50°F to 150°F, and 50% rh at 35°F to 85°F dewpoint at 120°F. The ceiling is perforated, allowing 30,000 cfm of conditioned air through any or all quadrants. A large door permits access to outdoors, and the floor is concrete with a temperaturecontrolled space underneath. Long-term control of temperature, humidity, and air motion permits development of standard test methods for freezers, coolers, refrigerated spaces or vehicles, heated enclosures, air conditioning systems or large components, heating systems and large humidifying or dehumidifying equipments. A small dynamometer has a capacity of 15 hp.

The Thermal Conductivity Laboratory has a very uniform temperature control; being underground, it is effectively shielded from outdoor temperature variations. Equipment available can take measurements from -196°C (-320°F) to 1200°C (2200°F) on glass, ceramics, pure metals or alloys, in air, vacuum, argon, or helium. The NBS Guarded Hot Plate Apparatus is the standard method of ASTM C177 for absolute determination of the thermal conductivity of dry speciments of good insulators; its range is 0.1 to 10 Btu per hour ft (°F/in.), or 0.15 to 15 milliwatts per cm °C from 0 to 130°F (-18 to 54°C).

Availability: To any qualified guest worker, to the extent consistent with NBS requirements; to other Government agencies on request.

Literature:

[1] Anthony, R. B., National Bureau of Standards and Environmental Research, ASHRAE J., January 1967, pp. 75-88.

[2] Watson, T. W. and Robinson, H. E., Trans. ASME Heat Transfer 83C, 403, (1961)

[3] Peavy, B. A., J. Res. Nat. Bur. Stand. (U.S.)

67C, (2) 119 (1963)

Contact: Frank J. Powell, Chief of Thermal Engineering Systems Section, Building Research Building, Room B104, Phone 301-921-3501.

CALORIMETERS

Applications: Used to determine enthalpies of reaction at or near room temperature, for the purpose of obtaining enthalpies of formation, enthalpies of solution, and related thermodynamic properties of sub

stances.

Availability: Because of the complexity of the instrumention and the procedures of operation, use of this facility is limited to qualified members of the NBS staff or scientists, after specific training of perhaps two months. The facility may be used indirectly through cooperative or contractual research agreements.

Contact: Dr. G. T. Armstrong, Chief of Thermochemistry Section, Chemistry Building, Room B350, Phone 301-921-2131.

LOW TEMPERATURE ADIABATIC CALORIMETER. The adiabatic calorimeter with associated cryogenic and vacuum equipment.

FLUORINE COMBUSTION
CALORIMETER

Solid samples may be reacted with fluorine gas in a nickel or monel 300 cm3 combustion bomb. Gas samples may be reacted in a flame (flow calorimeter) with a monel burner.

Capabilities: Fluorine or other reactive gases are stored in a special hood and are dispensed by a manifold having a pressure range from 10-5 micrometres mercury to 30 atmospheres. Both the manifold and calorimeters are located in a second safety hood. Under optimum conditions, the sample sizes should be such as to cause 40 kJ to be liberated as heat in the reaction. Under these conditions energies or enthalpies of reaction may be determined with a precision of better than 0.02%. Auxiliary equipment is available to handle and prepare samples.

The combustion vessel is located in a stirred-water isoperibol calorimeter. The temperature of the calorimeter jacket is held constant to within 0.001°C. Calorimeter temperatures are measured by a quartzoscillator sensor with digital printout. The calorimeter is calibrated electrically. Reduction of temperaturetime data is carried out by a time-shared computer.

LOW TEMPERATURE ADIABATIC CALORIMETER

This instrument was designed and built at NBS to make high accuracy heat capacity measurement for characterization of the thermodynamic properties of materials. The instrument is automated for round-the-clock operation.

Capability: Specimens in solid or liquid state compatible with gold plated copper cell. Temperature range, 2 to 380 K with ±0.001K accuracy (referenced to IPTS 1968). Heat capacity accurate to 0.05%. A lower accuracy scanning mode is being considered for alternative operation in the future.

Applications: Low temperature thermodynamic properties; glass transition; heats of fusion and transition; comparison of glass and crystal states; zero point entropies; sensitive measure of glass transitions using thermal drifts; detection of small effects of thermal history.

Availability: Operation under the direct supervision of Dr. S. S. Chang. Measurements of mutual interest can be arranged with NBS and other government personnel in accord with agreement.

Literature:

[1] K. F. Sterrett et al, An adiabatic calorimeter for the range 10 to 360 K, J. Res. Nat. Bur. Stand. (U.S.) 69C, 19 (1965).

[2] S. S. Chang and A. B. Bestul, Heat capacities of Cis-1, 4-polyisoprene from 2 to 360 K, J. Res. Nat. Bur. Stand, 75A, 113 (1971). Contact: Dr. Martin G. Broadhurst, Chief of the Dielectric and Thermal Properties Section, Polymer Building, Room B318, Phone 301-921-2748.

MICROCALORIMETRY

Capability: The facility provides the capability for measuring small thermal power (uncertainty within ±10μW) associated with (a) energies of reaction in aqueous solution at 300 K; (b) energies of transition over the range 300 to 470 K; and (c) energies of vaporization from 300 to 470 K. A commercial Calvettype microcalorimeter and NBS-designed microcalorimeters are available, utilizing the basic principles of heat conduction microcalorimetry.

A thermopile is used to measure the temperature difference between the reaction vessel and a heat sink maintained at constant temperature. Measurement of the emf of the thermoelement as a function of time yields a measure of the rate of heat exchange. Resolution of the thermoelement voltage to within a few nV corresponds to a temperature sensitivity of a few tenths of a microdegree. Data are recorded both in analog and in digital form. For calibration purposes, electrical energy may be introduced with a precision better than 0.01%.

Applications: Many applications are found in the biological sciences where heat, as a totally non-specific entity, has been found to be a useful tool for studies involving enzyme catalyzed reaction, bacterial metabolism, cellular phenomena, and immunological processes. Since nearly all reactions of biological substances are accompanied by heat effects, microcalorimetry also possesses substantial potential for analytical purposes.

Availability: Because of the complexity of the instrumentation and the procedures of operation, use of the facility is limited to qualified members of the NBS staff or other scientists, after specific training of perhaps two months. The facility may be used indirectly through cooperative or contractual research agreements.

Literature:

[1] E. Calvet and H. Prat, "Recent Progress in Microcalorimetry," translated from the French by H. A. Skinner, The MacMillan Company, New York, 1963.

[2] "Biochemical Microcalorimetry," H. D. Brown, editor, Academic Press, New York, 1969.

[3] R. N. Goldberg, R. L. Nuttall, E. J. Prosen, and A. P. Brunetti, NBS Report No. 10 437 (1971).

Contact: Dr. G. T. Armstrong, Chief, Thermochemistry Section, Chemistry Building, Room B350, Phone 301921-2131.

Typical specific data for different standard reference materials of polyethylene, using the LOW TEMPERATURE ADIABATIC CALORIMETER. The second-order glass transition is evident for the sample with the largest C, around 240 K.

PLATINIUM-LINED

ADIABATIC SOLUTION CALORIMETER

Capability: Liquid or crystalline samples up to 2.7 cm in volume are dissolved in 300±15 cm3 of any solution reactant that does not attack platinum. Minor modifications permit the introduction of gaseous samples in a flow system. For exothermic or endothermic reactions of 200 J or more, enthalpies of solution may be measured between 293 and 363 K for both rapid and slow reactions, with a precision of 0.02%.

Calorimeter temperatures are measured with a quartzoscillator sensor with digital printout. The adiabatic shield temperature is controlled automatically to eliminate heat transfer to the calorimeter from its environment. The data are processed by a time-shared computer. The calorimeter is calibrated by supplying a known amount of electrical energy to the calorimeter resistance heater before and after the chemical reaction measurements.

Applications: Used to determine enthalpies of reaction at or near room temperature, for the purpose of obtaining enthalpies of formation, enthalpies of solution, and related thermodynamic properties of substances.

Availability: Because of the complexity of the instrumentation and the procedures of operation, use of the facility is limited to qualified members of the NBS staff scientists, after specific training of perhaps two months. The facility may be used indirectly through cooperative or contractual research agree

ments.

Literature: Prosen, E. J., and Kilday, M. V., J. Res. Nat. Bur. Stand. (U.S.) 77A, 179 (1974).

Contact: Dr. G. T. Armstrong, Chief of Thermochemistry Section, Chemistry Building, Room B350, Phone 301-921-2131.

ROTATING

PLATINUM-LINED,
ADIABATIC BOMB
CALORIMETER

Capability: Solid or liquid samples are reacted with oxygen at 30 atm pressure in a 100 cm3 combustion bomb. The type of sample is limited only in that the products of the reaction must not be any chemical species that attacks platinum. A uniform concentration of aqueous products is assured by continuous rotation of the calorimeter. Amounts of sample are normally such as to cause 2500 J to be liberated as heat in the reaction. Under optimum conditions, the energy of reaction can be determined between 298 K and 323 K with a precision of better than 0.005%. Calorimeter temperatures are measured potentiometrically with a platinum resistance thermometer as the sensor. The adiabatic shield temperature is controlled automatically to eliminate heat transfer to the calorimeter from its environment. Determination of the amount and products of reaction can be determined by measurement of the amount of CO2 gas formed, and by analysis of aqueous solution constituents.

Applications: Used to determine enthalpies of reaction at or near room temperature, for the purpose of obtaining enthalpies of formation, enthalpies of solution, and related thermodynamic properties of substances. Availability: Because of the complexity of the instrumention and the procedures of operation, use of this. facility is limited to qualified members of the NBS

staff or other scientists, after specific training of perhaps two months. The facility may be used indirectly through cooperative or contractual research agree

ments.

Contact: Dr. G. T. Armstrong, Chief of Thermochemistry Section, Chemistry Building, Room B350, Phone 301-921-2131.

COMPUTER

CENTRAL

COMPUTER FACILITIES

The NBS Central Computer Facilities are available on a fee-for-service basis to support Government programs. In addition to Federal agencies, certain state and local government agencies, non-profit organizations, universities and private organizations, may qualify for use of the facilities. Service can be provided to non-Federal agencies on joint projects or for work that cannot be done effectively in the private sector. Arrangements can often be made to process work through remote terminals.

Facility Overview: The main computer in the NBS Central Facility is a UNIVAC 1108. The present operating system, EXEC 8, is a general purpose executive designed to operate in a multiprogramming environment which provides for a variety of user options. Access to the main computer is provided to both onsite users and those at remote terminals connected via telecommunications. Software support includes FORTRAN, COBOL, ALGOL, FLOWGEN (Automatic Flow Chart Generation), XBASIC, and OMNITAB (a computer language developed at NBS for statistical and numerical analysis).

Univac 1108: The UNIVAC 1108 includes 262,144 thirty-six-bit words of 750 nanosecond core memory. Auxiliary high-speed (1,440,000 characters per second) drum storage of approximately 25-million characters capacity provides for efficient workload control and swapping of executive program files. Other drum storage of approximately 925-million characters (FASTRAND mode) provides the needed capacity for on-line storage of application programs and data files. In addition, the system configuration includes eight seven-track VIII-C Tape Drives (200, 556, 800 CPI), two nine-track VIII-C Tape Drives (800 CPI), one 758 high-speed Printer, one 1403 off-line Printer, one 1004 Reader/Printer, one 1004 Card Punch, one highspeed Card Punch (300 CPM), and one high-speed Card Reader (900 CPM).

ACCELERATORS

LINEAR ELECTRON ACCELERATOR. Linac beam handling system.

ELECTRON

VAN DE GRAAFF

ACCELERATOR, 4 MeV

This accelerator, based on the principle of the Van de Graaff electrostatic generator, produces both continuous and pulsed beams of electrons with good energy resolution and continuous control of beam current and energy. Its capabilities make possible a wide variety of experiments using electrons or photons. Capability:

ENERGY: continuously variable 0.8 to 4.0 MeV.
ENERGY SPREAD: 0.2 percent.

OUTPUT CURRENT: 10" to 10" ampere dc.
500 microamperes peak
current pulsed.

PULSE LENGTH: 1 microsecond.
REPETITION RATE: 50 to 500 pps or single shot.
EXPERIMENTAL ROOMS: two, well shielded,
total area 200 m2.

Applications: Interactions of electrons and photons with matter; dosimetry measurements; isomer activation; electron channeling in solids; bremsstrahlung production studies; characteristic radiation production; nuclear activation; photofission experiments; radiation simulation measurements; radiation damage and failure studies.

agency and university users, industrial users, and guest workers. Operation only by qualified X-Ra Physics Section staff, under Dr. Charles E. Dick.

Literature: NBS Technical News Bulletin, August 1962 Vol. 46, No. 8, pages 107-110.

Contact: Dr. J. W. Motz, Chief of Applied Radiation Division, Radiation Physics Building, Room C216 Phone 301-921-2201.

EXPERIMENTAL ROOMS: three, with personne

access to one while beam is directed into another.

An on-line data handling system is available, and data reduction programs are available. Applications: Neutron total cross section measurements by time of flight (above-ground facility); new tron fission yields; neutron flux standards; neutron capture cross sections; fast neutron activation ana' sis; electron and photon dosimentry; pulsed radic sis of biochemical systems; electron scattering; elec trodisintegration of light nuclei; photonuclear physic with monoenergetic and polarized photons; photo activation analysis; dosimetry and dose distribution using radiochromic dyes; electron and photon bea measurement standards; production of radioactive

sources.

Availability: Beam time is available to NBS staff, othe agency and university users, industrial users, and guest workers. Operation only by qualified Linac Operations Section staff under J. E. Rose.

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